1. Field of Invention
The present invention relates to ships or other watercrafts, and more particularly to a high-speed watercraft with low sailing resistance, high propulsion efficiency and high speed, and also to a hovercraft without lift fan, whose stability is sufficient, load capability is large and energy consumption is low.
2. Description of Related Arts
The conventional hovercraft mainly relies on the effect of lift fans for forming a high-pressure air cushion under the bottom, in such a manner that the hull is lifted above the water, and the resistance of water when sailing is greatly reduced. Not only the sailing speed is high, but also adaptability is sufficient. However, because both the lifting device and the driving device are needed, the conventional hovercraft when sailing consumes a large amount of lifting power, even above 50% of the total power, which increases a manufacture cost of the conventional hovercraft, as well as lowers operation economy.
PCT/2011/079078 disclosed a sidewall planing boat, which is a previous application of the inventor of the present invention. The ship has a parallel trimaran structure. Sub-bodies of the boat are mounted on a front portion of a body and are provided at two sides of the body. And continuous rigid sidewalls are mounted at sides of the boat. Bottom surfaces of the sub-bodies are lower than a bottom surface of the body, whereby an angle is formed between the bottom surface and a water surface. Therefore, during high-speed sailing, air in front of the boat is pressed into a lifting area under the boat for forming three air cushions, in such a manner that the hull is lifted above the water. The boat according to the previous application not only lowers the water resistance and archives a high speed, but also excludes lift fans and lowers power consumption. Therefore, the technical effect is sufficient. However, the boat according to the previous application still has disadvantages as follows. On one hand, an upper space of the sub-body is not occupied, which narrows a passenger cabin on the hull and affects application of the boat. On the other hand, because the three air cushions formed under the hull are separated from each other, a total width and a total area of the air cushions are decreased, whereby the load capability and stability of the whole hull are insufficient.